1. Field Of the Invention
This invention relates to method and apparatus for actuating a normally closed valve by fluid flow to the inlet port of the valve, and, more particularly, to a hydrant-type valve that is opened when fluid pressure is applied to the inlet port of the valve and is closed when fluid flow to the inlet port is terminated.
2. Description of the Prior Art
Pressure medium actuated valves, also known as flow control valves, effect an opening or closing of a valve in response to pressurized flow to the inlet of the valve. A pressure medium activated valve is distinguished from a valve which is manually or automatically closed or opened upon demand. With a conventional valve an external force, other than fluid flow with the valve, is required to operate the valve between the open and closed positions. However, as disclosed in U.S. Pat. No. 4,285,495, emergency conditions may arise where the externally applied operating force may be impaired requiring that means be provided for immediately closing the fluid line without depending upon the availability of an externally supplied motivating force.
U.S. Pat. No. 4,285,495 discloses a safety valve which is normally closed, and in the absence of an externally supplied motivating force remains closed, or, if opened, immediately moves to the closed position. To open the valve, a positive fluid pressure must be supplied to the valve. The valve remains open as long as the externally supplied fluid pressure is available. In the event of an emergency, such as explosion, fire or the like, the externally supplied fluid may be removed by automatic means. The removal of the externally supplied pressure causes the valve to close. In the present application the valve is fail safe and is closed at all times except in the presence of a positively supplied actuating fluid pressure signal to open the valve.
In the operation of the above described safety valve, the fluid pressure required to open the valve is introduced externally of the valve. The biasing force of a spring that maintains the valve member in sealing engagement with the valve seat is overcome. The fluid flow into the inlet of the valve does not open the valve. A separate inlet through the valve body into the valve chamber is required. In other words, an external pressure signal separate from the inlet flow to the valve is required to open the valve. In the event the pressure signal fails, the valve automatically closes.
Conventionally, pressure medium actuated valves include a valve member or piston movable between an operative position corresponding to an open valve and a safety position corresponding to a closed valve. A spring is generally used to bias the piston toward the safety position. Operation of the valve to the safety position requires external pressure lines which connect a pressure chamber with subchambers divided by the piston. The piston is retained in the operative position by flow of a pressurized medium to the valve. To close the valve, the piston is moved to the safety position via the connecting line between the pressure chamber and the piston chamber.
U.S. Pat. No. 4,589,627 discloses a pressure medium actuated valve having a valve chamber, an inlet for conveying a pressure medium to the chamber, an outlet for conveying pressure medium from the chamber, and a cylinder sealingly spaced from the chamber. A piston is reciprocally positioned in the cylinder to divide the cylinder into a first chamber which enlarges upon movement of the piston from an operative position to a safety position and a second chamber which decreases upon the piston movement. A spring normally biases the piston toward the safety position. The flow of pressurized medium to the respective piston chambers is supplied through relief lines having control valves. The same pressure medium supplied to the inlet is supplied to external control lines operated by valves. While the pressure medium to the inlet of the valve controls the operation of the valve, external lines are connected to the valve body, increasing the overall complexity of the valve construction.
An early version of the above described control valves is disclosed in U.S. Pat. No. 385,521. A spring biased valve member is normally maintained in the closed position as long as the chamber connected to the inlet receives a pressurized flow which when combined with the spring force maintains the valve member seated or in a closed position. In the absence of fluid flow into the inlet, the valve member is maintained seated in the closed position by the spring force. When the fluid flow is supplied to the chamber below the piston equal to the pressure in the chamber above the piston, the valve member is displaced from the valve seat to open the valve and allow passage of fluid from the inlet to the outlet of the chamber. In a second embodiment, equalization of the fluid pressure above and below the piston is accomplished by the provision of an electrically controlled valve for supplying pressure below the piston. In both embodiments an external connection is required for supplying the needed pressure medium in addition to the inlet flow to the valve to open the valve.
The opening and closing of a spring biased valve disclosed in U.S. Pat. No. 3,980,270 is controlled by a solenoid operated pilot valve built into the valve body. The inlet to the valve is axially aligned with a valve member positioned on a valve seat between the inlet port and an outlet port extending at right angles to the valve chamber above the valve seat. The valve member is normally maintained by spring bias on the valve seat. The pilot valve closure member extends transversely or across the inlet port to engage in the normally closed position a valve seat leading to a relief channel. Actuation of the electric solenoid displaces the pilot valve member from the valve seat. This diverts fluid from the inlet port into a chamber which applies a force against the opposing spring bias to move the valve member off of the valve seat and open the valve for flow to the valve outlet.
A hydrant-type valve used in a water sprinkler supply line is disclosed in U.S. Pat. No. 3,727,630. Two embodiments of a control valve are shown for supplying water through a pipe to sprinklers. The valve includes an upright cylindrical structure having an inlet port positioned below an outlet port which extends transverse to flow into the inlet port. In one embodiment, the valve is opened and closed by a manual rotation of the valve stem to move a stopper into and out of sealing engagement with the valve seat. In another embodiment, flow through the inlet port is directed to an axial passageway to urge the valve member to a closed position. The axial flow to the valve stem is directed internally in the valve body through an internal passageway maintained closed by a stopper which is actuated by a solenoid. Energizing the solenoid from an external electrical supply displaces the control stopper to permit flow through the valve to apply a force upon the valve stem. The valve member is displaced from the valve seat so that water passes into the pipe leading to the sprinklers. When the solenoid is deenergized, the control stopper moves to the closed position, displacing the liquid pressure acting on the valve stem so that the fluid flow into the valve forces the valve member against the valve seat to close the valve.
Other examples of solenoid operated valves for actuating a control valve are disclosed in U.S. Pat. Nos. 3,114,532 and 4,285,493 and published UK Patent Application 2,065,929 A. An example of a flow control valve which permits symmetrical or generally straight line flow through a valve body or housing is disclosed in U.S. Pat. No. 2,976,880.
Pressure medium actuated valves are known to control the movement of a valve member into and out of an operative position relative to a valve seat by the pressure of the medium flowing through the valve. With the known devices an externally supplied actuating pressure signal is required to move a valve member to an open or closed position. The actuating signal may be provided by an electric solenoid which controls the valve for directing a portion of the fluid into the valve to displace the valve member from the valve seat. The conventional devices require complex fittings applied externally to the valve housing. The same complexity in the construction of the valve is encountered when manual means is utilized to actuate the valve.
In many applications there is a demand for a hydrant-type arrangement in which a straight line or axial flow to the valve body is desired so that the inlet and outlet ports are axially aligned and not transversely displaced. This is required in applications where the valve must be exhausted of all fluid when it is closed to prevent retention of fluid in the valve. This becomes a problem when the inlet and outlet are not axially aligned in an upright position.
Therefore, there is need for a pressure medium actuated valve responsive to inlet flow to the valve to move the valve member between operative positions in a straight line path of the fluid flow without the requirement for external connections to the valve housing to actuate movement of the valve member.